For a charger you can use a TP4056 module, many of these have protection built-in. You can tell by them having two more small chips near the solder pads, and of those pads having 4, two for battery + and - , and two for whatever you are attaching that will be protected
you can usually find them by sth like tp4056 modulewith battery protection circuit
the ones with usb c usually are designed without the cc pulldown resistors and thus will usually only function with usb a to usb c cables
Most of them are around 3.6V, I just need some protection circuits and a way to charge them
For a charger you can use a TP4056 module, many of these have protection built-in. You can tell by them having two more small chips near the solder pads, and of those pads having 4, two for battery + and - , and two for whatever you are attaching that will be protected
you can usually find them by sth like
tp4056 module with battery protection circuitthe ones with usb c usually are designed without the cc pulldown resistors and thus will usually only function with usb a to usb c cables